hi
i have just acquired a capacitive pickup cable for my baby scope to view high tension voltage trace on an igniter circuit . its basically a crocodile clip that goes round the high tension lead connected to the center of the coax with an earth clip and one surface mounted component linking the center of the coax to the earth/shield wire.
how does it work as in the capacitive part.

 

ok so i think i understand a little more. correct me if im wrong
the clip forms one half of a capacitor the other half being the conductor of the hi tension voltage. the oscilloscope is connected to the clip plate and the earth to the body of the igniter electrode holder to complete the circuit. the oscilloscope then shows the relevant voltage/charge of this capacitor set up.
now just to work out what the surface mount component is.